Giant Slalom Research Articles

Aerodynamic drag is not the major determinant of performance during giant slalom skiing at the elite level

This investigation was designed to (a) develop an individualized mechanical model for measuring aerodynamic drag (F(d) ) while ski racing through multiple gates, (b) estimate energy dissipation (E(d) ) caused by F(d) and compare this to the total energy loss (E(t) ), and (c) investigate the relative contribution of E(d) /E(t) to performance during giant slalom skiing (GS). Nine elite skiers were monitored in different positions and with different wind velocities in a wind tunnel, as well as during GS and straight downhill skiing employing a Global Navigation Satellite System. On the basis of the wind tunnel measurements, a linear regression model of drag coefficient multiplied by cross-sectional area as a function of shoulder height was established for each skier (r > 0.94, all P < 0.001). Skiing velocity, F(d) , E(t) , and E(d) per GS turn were 15-21 m/s, 20-60 N, -11 to -5 kJ, and -2.3 to -0.5 kJ, respectively. E(d) /E(t) ranged from ∼5% to 28% and the relationship between E(t) /v(in) and E(d) was r = -0.12 (all NS). In conclusion, (a) F(d) during alpine skiing was calculated by mechanical modeling, (b) E(d) made a relatively small contribution to E(t) , and (c) higher relative E(d) was correlated to better performance in elite GS skiers, suggesting that reducing ski-snow friction can improve this performance.

Course setting and selected biomechanical variables related to injury risk in alpine ski racing: an explorative case study

BackgroundCourse setting has often been discussed as a potential preventative measure in the World Cup ski-racing community. However, there is limited understanding of how it is related to injury risk.ObjectiveThis...

Aerodynamic Drag Modeling of Alpine Skiers Performing Giant Slalom Turns

Aerodynamic drag plays an important role in performance for athletes practicing sports that involve high-velocity motions. In giant slalom, the skier is continuously changing his/her body posture, and this affects the energy dissipated in aerodynamic drag. It is therefore important to quantify this energy to understand the dynamic behavior of the skier. The aims of this study were to model the aerodynamic drag of alpine skiers in giant slalom simulated conditions and to apply these models in a field experiment to estimate energy dissipated through aerodynamic drag. The aerodynamic characteristics of 15 recreational male and female skiers were measured in a wind tunnel while holding nine different skiing-specific postures. The drag and the frontal area were recorded simultaneously for each posture. Four generalized and two individualized models of the drag coefficient were built, using different sets of parameters. These models were subsequently applied in a field study designed to compare the aerodynamic energy losses between a dynamic and a compact skiing technique. The generalized models estimated aerodynamic drag with an accuracy of between 11.00% and 14.28%, and the individualized models estimated aerodynamic drag with an accuracy between 4.52% and 5.30%. The individualized model used for the field study showed that using a dynamic technique led to 10% more aerodynamic drag energy loss than using a compact technique. The individualized models were capable of discriminating different techniques performed by advanced skiers and seemed more accurate than the generalized models. The models presented here offer a simple yet accurate method to estimate the aerodynamic drag acting upon alpine skiers while rapidly moving through the range of positions typical to turning technique.

Testing of fabrics for use in alpine ski competition suits

This paper describes the process of testing fabrics for use in alpine ski competition suits for the Norwegian national team. The main goal of the project was to indentify the aerodynamically best currently available fabric for use in Slalom, Giant Slalom and Super G/Downhill suits for the 2011/2012 competition season. A selection of fabrics were selected and tested in a wind tunnel on cylinder models of varying diameters and on an airfoil model. Additional measurements were performed with increased stretching in order to identify how this would alter the performance of the fabrics. The fabrics tested showed a large spread in critical velocity, minimum drag coefficient (CD) and supercritical drag characteristics, clearly illustrating the need to individualize fabrics for each of the alpine competition disciplines according to average race speeds. Full race suits were made from three of the fabrics and tested on athletes. These measurements confirmed the trend from the model measurements, although the variability in these measurements was too large to make a reliable estimate of actual drag reduction.

Structure of Qualitative Development of Techniques and Division of the Skill Level in Giant Slalom of Alpine Skiing Competition

Structure of Qualitative Development of Techniques and Division of the Skill Level in Giant Slalom of Alpine Skiing Competition

Erythropoietin, 2,3 DPG, Oxygen Transport Capacity, and Altitude Training in Adolescent Alpine Skiers

Rapid growth during adolescence caused by metabolic changes and their metabolic response to anaerobic and aerobic exercise differs considerably from that in adults and this is especially true in the responses to stresses, such as altitude exposure. However, there is little information on the suitability of exercise training at altitude for young athletes. Six male Korean adolescent alpine skiers (13-17 yr), with a skiing career of 3-5 yr, participated in the study. All subjects were exposed to an altitude of 2700 m (8858 ft) for 5 wk and altitude exposure consisted of 6 d/wk of training (4-5 h/d), with living quarters at 2100 m (-6890 ft) (Tignes, France). The 5 wk of ski training at altitude were maintained at the same level (the same number of slalom and giant slalom skiing trials) as at sea level. There was a significant increase in oxygen transport capacity, despite decreased erythropoietin (EPO) production (-31%) after altitude training. Red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), and 2,3 DPG concentrations increased significantly during altitude exposure and after return to sea level. Results indicate that applying altitude training in adolescent skiers may improve their endurance performance. However, EPO production during altitude training needs to be evaluated in larger future studies.

우수 알파인스키 선수의 세부 종목에 따른 유,무산소성 능력 특성

The study was to out fitness characteristics of Slalom skiers and Giant slalom skiers on comparative analysis of aerobic power and anaerobic power. Original fitness according to performance of Slalom skiers and Giant slalom skiers and study was to make use of the finding for the purpose of upgrading Slalom skiers and Giant slalom skiers fitness training and evaluation. The surveyed of the test include top16 rankers of the national representative team. The groups were divided into two groups; Slalom skiers and Giant slalom skiers. For measurement of aerobic power, an automatic breath gas analyzer QMC(Quinton Co. USA), Q4500 was employed to measure VO(2)max, RER, HRmax, At, and HRrest. For measurement of anaerobic power, Wingate anaerobic power analyzer employed. Monark(SWEDEN)was employed to inspect a basic fitness condition. According to results, the following conclusion were obtained. 1. In case of inspection of aerobic power, HRmax, VEmax, AT, VO(2)max, were high in the group of Slalom skier but there was a significant difference in VO(2)max and AT(p.05). 2. In case of inspection of anaerobic power, the group of slalom skier and there was significant difference in peak power and endurence racio (p.05).

Seasonal variation of bone turnover markers in top-level female skiers

Different levels of weight-bearing activities imply different levels of anabolic effects on skeletal tissue and this can be assessed by measuring biochemical markers reflecting bone metabolism. With this study we wanted to determine how the serum levels of bone turnover markers change during different phases of annual training in elite female skiers. Fourteen top-level Caucasian athletes, from the Italian Women's Alpine Ski Team (slalom and giant slalom), were tested at the end of the relative rest period (T1), the pre-competitive season (T2) and the competitive season (T3). Serum levels of bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase (TRAP5b) activities and of osteocalcin (OC), and crosslaps (the carboxyterminal crosslinked telopeptide of type I collagen--β-CTx), were assayed together with the determination of 25(OH)D levels. The formation markers, BAP and OC and the resorption marker TRAP5b significantly increased from T2 to T3, while crosslaps showed no significant changes. The peculiar trends of bone formation markers correlated one to each other at T2 versus T3, and this was probably linked to the highly demanding period of competitions when, in athletes performing weight-bearing exercise, bone is more stimulated by mechanical forces. 25(OH)D levels, instead, changed from T1 to T2 and from T1 to T3 and its trend do not show any correlation with that of bone markers. In conclusion, we found that both the bone formation markers and TRAP5b, marker of resorption, are significantly increased from the pre-competitive season to the competitive season.

Critical appraisal and hazards of surface electromyography data acquisition in sport and exercise.

The aim of this critical appraisal and hazards of surface electromyography (SEMG) is to enhance the data acquisition quality in voluntary but complex movements, sport and exercise in particular. The methodological and technical registration strategies deal with telemetry and online data acquisition, the placement of the detection electrodes and the choice of the most adequate normalization mode.Findings compared with the literature suggest detection quality differences between registration methods and between water and air data acquisition allowing for output differences up to 30% between registration methods and up to 25% decrease in water, considering identical measures in air and in water. Various hazards deal with erroneous choices of muscles or electrode placement and the continuous confusion created by static normalization for dynamic motion. Peak dynamic intensities ranged from 111% (in archery) to 283% (in giant slalom) of a static 100% reference. In addition, the linear relationship between integrated EMG (IEMG) as a reference for muscle intensity and muscle force is not likely to exist in dynamic conditions since it is muscle - joint angle - and fatigue dependent. Contrary to expectations, the literature shows 30% of non linear relations in isometric conditions also.SEMG in sport and exercise is highly variable and different from clinical (e.g. neurological) EMG. Choices of electrodes, registration methods, muscles, joint angles and normalization techniques may lead to confusing and erroneous or incomparable results.

Factors affecting the aerodynamic drag of alpine skiers

This paper documents a five year testing program that identified factors affecting the aerodynamic drag (Fd) of alpine skiers. Wind tunnel Fd measurements of world class alpine skiers and air permeability measurements of ski suits were conducted to determine the effect of fabric permeability on suit Fd. Frontal area (Ap) measurements were combined with Fd data to determine the drag coefficient (Cd) of the athletes in various skiing positions. Differences in Fd of ski suits were most pronounced between downhill (DH) race suits and those designed for Giant Slalom (GS) competition where protective padding increased Fd by up to 7.1%. In general, suits that were stretched from multiple wearing or that were undersized had greater permeability and higher Fd. Alternatively, skiers who wore a loose fitting suit or multiple suits that increased the skier’s Ap experienced up to 5.2% of additional Fd, estimated to slow a skier by 0.19 s over a 250 m straight glide section of a downhill race course. Pre-season wind tunnel testing to optimize body positioning and ski suit size selection, followed by custom suit fitting have been important to the competitive success of the Canadian Alpine Ski Team.

Alpine Skiing and Anaerobic Performance in Solid Organ Transplant Recipients

Limited information has been published about sporting activities in solid organ transplant recipients. The aim of this study was to assess “in the field” performance capacities of a group of transplant recipients involved in an alpine skiing competition. We studied 16 transplant recipients (13 men and 3 women) who had undergone transplantations (11 kidney, 4 liver, and 1 heart) at 89 ± 68 months prior while participating in an alpine skiing race. The patients performed a countermovement jumping test to measure the explosive power of the lower limbs. In all patients blood lactate concentrations (La) were measured at the end of a giant slalom race. The maximum displacement of the center of mass during the jumping test was 22.4 ± 9.3 cm; the time to complete the giant slalom was 75.5 ± 16.5 seconds and La was 3.5 ± 0.8 mmol/L. We observed significant linear relationships between race time and La ( R 2 = 0.4733; P < .01) and between race time and performance in the jumping test ( R 2 = 0.3655; P < .05). This study indicated that recovery of anaerobic and technical sporting activities is possible in organ transplant recipients. Muscular power and anaerobic performances among a selected group of solid organ transplant recipients were similar to those of the general untrained population.

Right Shoulder Injury-skiing

HISTORY: A 16 year old male alpine ski racer sustained and injury to his right shoulder while crashing in a giant slalom training. He reported that it felt as if his shoulder was dislocated, it was terrible painful and he was unable to move it through any considerable range of motion. The ski patroller at the race course placed his arm and the athlete was brought to the medical doctor who placed his arm in external rotation and apparently reduced the shoulder. The arm was fixed at the trunc with a bandage. PHYSICAL EXAMINATION: The athlete was evaluated one week later for the complaint of apprehension and inability to return to ski competition 10 days after the injury. The right shoulder examination was significant for abnormal scapulothoracic rhythm with scapular hiking present but nearly full active abduction. Active internal rotation was limited to approximately 25 degrees and active external rotation to approximately 30 degrees. Passively slightly more motion was possible but produced significant pain. Strength was reduced within the available motion but again produced discomfort. Although apprehension signs were negative, Neer's, Hawkin's, O'Brian's and anterior glide tests were all positive. DIFFERENTIAL DIAGNOSIS: Labral tear (Bankart lesion), Hill Sachs lesio, Rotator Cuff impingement vs. strain or tear, AC joint lesion TEST AND RESULTS: Shoulder x-ray ap and lateral shows no pathological signs. Shoulder MRI: Hill Sachs lesion Tear in the anterior-inferior labral area (Bankart lesion) Rotator cuff muscles intact AC-joint intact FINAL WORKING DIAGNOSIS: Bankart and Hill-Sachs lesion TREATMENT AND OUTCOMES: Ice, Bandage for 10 days, manual lymph-massage, high-voltage electrotherapy, low-level-laser therapy Activity - training - modification Initial therapeutic exercise consisted of active and active assisted shoulder range of motion exercises in all planes Underwater therapy in closed chain exercises Scapular stabilisation exercises Gradually advances to a progressive shoulder girdle and rotator cuff strengthening programme as full pain-free motion returned Sport specific conditioning initiated 2 month post injury - starting with skiing with special bandage 3 months after injury return to competition was possible - no problems

Design of Ski Boots for Alpine Ski Racing Based on Leg Frame of the Skier

A ski boot is important to make progress in ski turning technique as an interface between a skier and a ski. Especially in alpine ski races, suitability of design of the boots for racers becomes more important to achieve accurate and quick lean of the leg in ski turns. This study is aimed at building a new design concept of a ski boot that can improve the results of alpine ski races. In this paper, new design of an upper shell of a ski boot that was adjusted to the features of the frame of alpine ski racers was experimentally examined. As a result, it was demonstrated that a front and a rear part of the upper shell of a ski boot should be separately adjusted to the length of a shank of each player for well-balanced quick lean of the leg in the ski turn. Finally, the effect of new design of an upper shell was examined in giant slalom and slalom tests by Japanese alpine ski racers of the first rank. Consequently, the results showed that lean angle during turns was increased and finish time was shortened when the skiers wore the newly designed boots.

Injuries among elite snowboarders (FIS Snowboard World Cup)

Background: Although snowboarding is already established as an Olympic sport, it is still a developing sport, with new disciplines, more demanding snow installations, and spectacular tricks. A recent study on...

Correlation Between Competition Time And Physical Fitness Variables Of Alpine Skiers At Super Giant Slalom

PURPOSE The purpose of this study was to provide effective off-season training program through comparing analysis to correlation between super giant slalom competition time and physical fitness variables of alpine skier. METHODS Seventeen male athletes(17.06 ± 1.75yr, 167.59 ± 8.13cm, 65.71 ± 11.58kg) of the Korea Ski School were involved in this study. Physical fitness test variables consisted in stand and reach, vertical jump, one leg stand, 10m shuttle run, side step, isokinetic knee and trunk test. Racing performance was defined by the competition time. The atheletes' aerobic performance capacity was assessed by maximal exercise testing on the treadmill. Anaerobic power was measured by wingate test(90's). The isokinetic muscle strength of the knee and back of extensor and flexor muscles were tested by Cybex 770. RESULTS Analysis of the data was accomplished by using the correlation with the significant level for hypothesis rejection at α =.05. There were significant correlations that super giant slalom between competition time and agility(r=−.673, p<.01), isokinetic knee extensor(r=−.836, p<.01), isokinetic back extensor(r=−.797, p<.01), vertical jump(r=−.820, p<.01), and anaerobic power(r=−.696, p<.01). However there was no correlation with flexibility, balance, and VO2max. CONCLUSIONS These data suggested that, in order to improve competition time of alpine skiers, instantaneous reactionary force, agility, anaerobic power, knee and back muscle strength should be trained during off-season training program.

Injuries among Competitive Snowboarders at the National Elite Level

Background Little is known about injury risk or the pattern of injuries among competitive snowboarders. Purpose To describe the incidence and pattern of injuries among female and male snowboard athletes at the highest national level. Study Design Descriptive epidemiology study Methods This study consists of 2 parts: prospective registration of injuries at snowboarding national cup events and the national championships during the 2002 season, as well as a retrospective interview of the participants during the national championships in March 2002. All injuries that resulted in missed participation were recorded. Exposure was recorded as the number of runs in all disciplines. Results In the prospective study, the competition incidence was 4.0 ± 0.7 injuries per 1000 runs (n = 32 injuries). Back (22%), knee (16%), and hand/wrist injuries (9%) were the most common. The incidence for the different disciplines was 14.2 ± 5.3 per 1000 runs for big jump, 6.1 ± 1.8 for snowboardcross, 3.1 ± 0.9 for halfpipe, and 1.9 ± 1.9 for giant slalom. The retrospective interview (n = 163 athletes, 83% response) revealed 84 acute time-loss injuries during the season; knee (16%), back (13%), head (13%), and hand/wrist injuries (12%) were the 4 most common injury types. The overall competition incidence was 3.4 ± 0.6 injuries per 1000 runs (6.6 ± 3.0 for big jump, 5.8 ± 1.7 for snowboardcross, 2.1 ± 0.7 for halfpipe, and 6.6 ± 4.7 for giant slalom). No injury was recorded in parallel slalom in either study. Conclusion The incidence of injuries is high among competitive snowboarders at the elite national level. The injury pattern is different from the panorama seen among less experienced athletes, with fewer wrist injuries and more knee injuries.

INJURIES AMONG COMPETITIVE SNOWBOARDERS AT THE NATIONAL ELITE LEVEL

Even though snowboard has become a popular sport rewarded with Olympic recognition, little is know about injury risk or the pattern of injuries among competitive snowboarders. In unselected materials, injuries to the wrist are frequent, representing more than 30% of all injuries. PURPOSE To describe the incidence and pattern of injuries among female and male snowboard athletes at the highest national level. METHODS Prospective registration of injuries at National Cup events (including the National Championship) during the 2002 season, as well as a retrospective interview of the participants during the National Championships March 2002. All injuries that resulted in medical assistance or missed participation were recorded. Exposure was recorded as the number of runs in all disciplines. RESULTS A total of 1465 participants took part in the 22 competitions of the prospective study (n = 8200 runs), and 32 injuries were recorded. There were 7 back (22%, 6 concussions), 5 knee (16%), 4 shoulder (13%) and 3 hand/wrist injuries (9%). The incidences for the different disciplines were: 14.2 per 1000 runs for big jump (n = 7), 6.1 for snowboardcross (n = 11, ns. vs big jump), 3.1 for halfpipe (n = 13, p < 0.001 vs big jump), 1.9 for giant slalom (n = 1, p < 0.05 vs big jump). No injury was recorded in parallel slalom. There was no difference in injury incidence between junior and senior athletes or between genders. The interview (n = 163 athletes, 83% response) revealed 90 injuries during the season with 15 knee injuries (17%), 11 back injuries (12%), 11 head injuries (12%), 9 shoulder injuries (10%) and 10 hand/wrist injuries (9%). Most of these injuries (69%) occurred outside competition. CONCLUSION The incidence of injuries among competitive snowboarders at the national top level is high, especially for big jump. The pattern of injuries is different from the panorama of injuries seen among less experienced athletes with fewer wrist injuries and moire knee injuries.

The Inaugural Winter Senior Olympic Games

Introduction: Regular exercise can slow physiological decline of aging by 50%. Competitive and sport oriented older adults represent a kind of “elderly elite” and provide a gold standard against which age-related physical decline can be compared (O'Brien & Conger, 1991). However, older athletes are at greater risk for cardiac events than younger adults. Safety issues are always of paramount importance with any competition, which is especially true with older adults. This pilot research project identified risk factors and subsequent precautions to older athletes through baseline screenings and physiological assessments conducted during their competitive events. Methods: This cross-sectional research project began profiling senior athletes (≥ 50 years of age) across multiple sports in terms of their physiological responses to competition. Subjects were recruited from the Winter Senior Olympic Games held in Lake Placid, New York in 2000. Data collection consisted of two phases: Phase I - informed consent, medical history questionnaires (MHQs), and baseline health screenings (resting heart rate and blood pressure, fasting blood work, body composition, etc.); and Phase II - physiological assessments (predicted, average and maximum heart rates, intensity level, pre- and post exercise blood lactate levels) assessed by Polar heart rate monitoring at several Olympic venues (See Table 1). The Statistical Package for the Social Sciences software package (version 9.0) was used for data entry and analyses. One-way ANOVA was used to determine differences between sports. All reported p values are two-tailed with an alpha of .05.Table 1Results: Of the 148 senior athletes assessed in Lake Placid, 59 alpine skiers and hockey players were tested during their events. Their ages ranged from 50–83 years (x = 62, ± 7.6), 77% were men; 98% were Caucasian. The MHQs asked about exercise safety practices including warm-up (77% men, 55% women), cool-down (55% men, 48% women) and monitoring heart rate during regular exercise (21% men, 14% women). Seventy six percent of the athletes engage in cardiovascular exercise year round and 13% do not perform any form of aerobic exercise. Based on the athletes' cardiovascular responses both hockey and the alpine (slalom and giant slalom) events would be classified as vigorous exercise (> 70% of maximum heart rate, MHR). Significant differences exist between the average heart rates sustained during the two sporting events (p = .01*) and the intensity of those events (p = .0001 ‡). Discussion: The majority of senior athletes fall in the “moderate risk” category identified by the American College of Sports Medicine (ACSM). This is mainly due to their ages (men ≥ 45 years, women ≥ 55 years) and they would be advised to have a graded exercise stress test (GXT) prior to engaging in “vigorous” exercise. However, only 21% of the athletes indicated they had had a GXT. Also, as evident in Table 1 the MHR achieved during both events places the intensity levels well into the “vigorous” exercise classification. Physical activity is perhaps the most obvious lifestyle variable by which overall lifetime morbidity and mortality might be reduced. However, the vast majority of these senior athletes lack the proper screening for safe and effective exercise programming especially when engaging in such high intensity sporting activities. Acknowledgements: Supported in part by a grant from Loma Linda University's Center for Health Research and T.E.A.M.

The influence of geographic variations on the muscular activity in selected sports movements

Surface EMG (SEMG) has been used frequently to study motion techniques or skills, body positions, material or equipment used, training-methodology and learning processes in sports and ergonomics. Little if any information is available on the effect of the geographical environment on the neuromuscular control of an athlete or workman during his/her performance or effort. Motions were chosen in Alpine skiing and cycling. Thirty-one certified ski instructors and twelve professional road cyclists participated in the study of geographical variance and its impact on muscle activity. SEMG was measured from the agonists and antagonists of the upper- and lower limb. Skiers were measured on downhill slopes ranging from 19 to 51% while the cyclists performed with different saddle positions on 2, 7 and 12% slope inclinations, respectively. Verification of the variation of muscular intensity (IEMG) over the slope inclination during a simulated giant slalom indicated that the muscular activity increased with increasing slope angle and decreased with decreasing slope angle, while heart rate measured with short-range radio telemetry increased at a constant rate between start and finish independent of the geographical variations. In a direct descent on different slopes % levels the integrated EMG is well related to the inclination ( r=0.82) confirming the findings of the giant slalom. In cycling we found that, regardless of the pelvis position, the muscular intensity of lower limb muscles increased with increasing slope inclination, while the muscular intensity of the arms decreased with the same increasing slope inclination. In addition the decreased intensity of the arm muscles remained significantly higher with the pelvis (saddle) fully forward. The geography of the terrain did influence the neuromuscular work and therewith probably the performance also. The influence however, varies with specific circumstances and is coupled with items of variability of the equipment used and the body regions involved.

KNEE INJURY - ALPINE SKING

HISTORY - A 29 year-old world cup skier sustained a knee injury while steering a giant slalom turn. He unintentionally used his usual ski technique, when he got a bump on his right knee. He felt a short but very severe pain and he fell down in a big crash. After the crash he could not lift his leg and he had a lot of pain but there was no numbness. He was not able to stand up. The trainer beside the course made a radio call to the team doctor. PHYSICAL EXAMINATION - Examination of athletic in ski wear on the sideline of the race course was done. It was not practicable to come to a final diagnosis under these conditions. A knee immobiliser and ice were applied and the ski racer was brought to the ambulance by the mountain rescue team and later to hospital. DIFFERENTIAL DIAGNOSIS distorsion of the knee ACL rupture with meniscus lesion rupture of the patellar tendon TEST AND RESULTS: EMERGENCY ROOM RADIOGRAPHS Knee joint anterior posterior and lateral. No osseous lesions. MRI shows a rupture of the patellar tendon, no lesions of the ACL, PCL, menisci and other soft tissues of the knee FINAL WORKING DIAGNOSIS: Total rupture of the patellar tendon TREATMENT AND REHABILITATION surgery with metal-loop fixation and knee-device fixed in 5° flexion for 5 weeks 10 days after surgery beginning of the underwater therapy-passive mobilisation between 5° and 10° electro stimulation manual techniques for patella-mobilisation 6 weeks after surgery gait training with special devices, therab and-exercises, isokinetics in closed chain modus 2 months after surgery enforcement of strengthening and stretching techniques proprioceptive training, gait analysis and video analysis - walking with poles increasing of intensity and endurance return to ski races 8 months after injury